Process of and apparatus for recovering the ammonia content of coal-gas



B. TORREY, JR.

PROCESS OF AND APPARATUS FOR RECOVEBING THE AMMONIA CONTENT OF COAL GAS.

APPLICATION FILED MAY 3, 1918.

1,349,393, Patented Aug. 10, 1920.

2 SHEEISSHEET l.

PROCESS OF AND APPARATUS FOR RECOVERING THE AMMONIA CONTENT OF COAL GAS.

APPLICATION FILED MAY 3, 1918- 1,349,'393. v Patented Aug. 10,1920.

2 SHEETSSHEET 2.

INVENTOR BY x fl a

- ATTORNEY umreo STATES PATENT omce.

BATES TORREY, JR., OF SYRACUSE, NEW YORK, ASSIGNOR TO SEMET-SOLVAY COMPANY, OF SOLVAY, NEW YORK, A CORPORATION OF NEW YORK.

PROCESS OF AND APPARATUS FOR RECOVERING THE AMMONIA CONTENT OF COAL-GAS.

T 0 all whom it may concern: I

Be it known that I, BATES TORREY, J r., a citizen of the United States, residing at Syracuse, in the county of Onondaga and State of New York, have invented certain new and useful Improvements in the Processes of and Apparatus for Recovering the Ammonia Content of Coal-Gas, of which the following is a specification.

My invention relates specifically to the treatment of gas produced by the destructive distillation of coal so as to recover its ammonia content by the passage of the gas through sulfuric acid with consequent con version of the ammonia into ammonium sulfate.

Any process directed to this end requires the removal from the gas of its tar content which, if allowed to remain would appear as an impurity in the product and also the removal, in recoverable shape, of the fixed ammonia compounds, consisting mainly of chlorid of ammonia, which, if allowed to pass on and be broken up in the acid bath produce chlorin compounds destructive of the apparatus.

The object of my improvements is to accomplish these results in a more simple and economical manner than heretofore and at the same time insure the practically complete recovery in the form of sulfate of the free ammonia content of the gas. To this end in carrying my invention into effect I in the first instance spray the hot gas as it comes from the ovens, in the collecting main, with water in such quantity that a largeproportion of it remains in the liquid state in the main. By this means the gas is cooled and the water is highly heated, and eventu ally, after removing from the gas its tar and fixed ammonia content, I utilize this hot water to again heat the gas and recharge it with water vapor, and free ammonia. In this manner I am able to return to the gas practically all the free ammonia produced in the system without the application of any extraneous heat whatever, with a consequent saving in fuel expense and with great simplicity of operation.

The invention will be best understood by reference to the accompanying drawings forming a part hereof, Figure 1 of which is a diagrammatic representation of an organization of apparatus which may be em- Specification. of Letters Patent.

Patented Aug. 10, 1920.

Application filed May 3, 1918. Serial No. 232,257.

the hydraulic main, reference being made thereto by means of the letters indicating the several parts.

Referring to the drawings, A indicates the collecting or hydraulic main in which the gas 'is received as it comes from the ovens (not shown in the drawing) through pipes, N. In this the gas is sprayed with water, by well known means, a form of which is shown in Fig. 2, by the vaporization of which the temperature of the gas is reduced to approximately 80 (J. A portion of the water is carried along with the gas in the form of vapor while another portion remains in the main in liquid form mixed with the tar therein. The water in the main, A, together with the tar, is drawn ofi', as by pipe 0, to a tank, B, where the tar settles out and is drawn 'off, while the water overflows to a subsidiary tank, 0. The gas from the main passes first to a scrubber, D, wherein it is showered with cooled water of condensation from the gas, this being drawn off from the bottom of the scrubber and continuously forced, as by pump, a, through cooling coils, E, which are'showered with cold water, and thence to the top of the scrubber, D.' By this scrubbing the gas, which comes from the main at a temperature of approximately 80 C. is cooled. A large proportion of its tar. content is removed and much of the water carried thereby is condensed, so that the fixed ammonia compounds, with more or less free ammonia, gointo solution.

The hot surplus water of condensation with its tar and ammonia content is drawn off as required by opening valve, 12, in pipe, 0, and is run to tank, B, and there mixed with the hot water drawn from the main, A.

After this initial scrubbing the gas, which will have been cooled to such low temperature as may be desired, preferably from 25 C. to 40 (1., is treated to remove any residue of tar remaining therein, as by being forced through a tar extractor, F, of any usual or suitable construction.

The gas is then passed through a scrubber or wash tower, G, in which it is showered with water heated in the hydraulic main, which is drawn from the bottom of tank, 0,

I evident to those skilled in the art since it thus avoiding the light tar oils which float on thesurface ofthe water in tank, C, and are drawn off by surface overflow to tank, H. The hot water is then forced to the top of tower, G, as by pump, 9.

The water enters the scrubber at a temperature of approvimately 75 C. and by this scrubbing the previously cooled gas is heated to a temperature of from 65 C. to and is charged with water vapor and takes up and carries along the free ammonia in the wash water. From the wash tower, G, the gas passes to a saturator, I, of any usual or suitable type wherein its ammonia content combines with sulfuric acid to form sulfate of ammonia in the usual manner and the gas passes on to be collected and treated for utilization as desired.

The unvaporized water from the scrubber, G, flowsby pipe, 2' to tank, H, whence it is returned, as by pump, is, through pipe, P, and branch pipes, p, p, to the main, A, to be again used in spraying the gas. Thus a continuous circulation of the water in the system is maintained and the heat imparted to the water by the hot gas in the main, A, is utilized in heating the gas in the scrubber, G, without the application of any extraneous heat.

In order to avoid the loss of ammonia in the fixed form due to its concentration and crystallization in the solution a portion of the solution may be drawn oif from time i to time from tank, H, and treated in anysuitable manner as by the well known lime treatment for the recovery of its fixed ammonia content. The ammonia thus liberated may be added to the gas passing fromv the wash tower, G, to the saturator. The water thus withdrawn from the system and that taken up by the gas in the wash tower, G, may be compensated for by an inflowof fresh water as required from time to time to tank, H.

The advantages of my invention will be provides a system extremely simple both in apparatus and method of procedure, in which the tar and free ammonia are automatically separated and the latter recovered in the desired form without the necessity of any critical observation of temperatures and without the use of any extraneous heat to restore the free ammonia to the gas. The ready recovery of the fixed ammonia is also provided for so that there is no loss from this source.

What I claim as new and desire to secure by Letters Patent is:

1. The process of recovering the ammonia content of coke oven gas, which consists in heating water in the hydraulic main by the initial heat of the gas as it comes from the ovens, washing and cooling the gas to remove tar and fixedammonia therefrom, re-

heating the gas by washing it with said heated water and finally passing the gas through an acid bath-to form sulfate of ammonia.

2. The process of recovering the ammonia content of coke oven gas which consists in heating water in the hydraulic main by.the initial heat of the gas therein, washing and cooling the gas to remove tar and fixed ammonia therefrom by cooling and circulating in contact with the gas water of condensation therefrom, reheating the gas by washing it with said heated water and finally passing the gas through an acid bath to form sulfate of ammonia.

3. The process of recovering the ammonia content of coke oven gas which consists in spraying the gas in the hydraulic main as it comes from the oven with water in such quantity as to leave a material part thereof -in liquid form in the main whereby the water is heated, washing and cooling the gas to remove .tar and fixed ammonia therefrom by cooling and circulating in contact therewith water of condensation from the gas and returning the surplus water of condensation to the water initially heated by the gas, removing its free ammonia content from the heated water by washing the gas therewith thus heating the gas and adding thereto water vapor and free ammonia and recovering the ammonia from the gas, and returning the surplus wash water to again spray the gas coming from'the oven.

4. The process of recovering the ammonia content of coke oven gas which consists in spraying the gas in the hydraulic main as it comes from the oven with water, drawing off the gas from the main and removing tar and ammonia therefrom and thereby heating the water, continuously drawing off and circulating the water from the main and returning it to spray the gas as it comes from the oven therewith and in the course of such circulation washing the gas with the water thereby restoring ammonia thereto and finally passing the gas through an acid bath to form sulfate of ammonia.

5. In apparatus for recovering the ammonia content of coal gas the combination with a hydraulic main and means for delivering gas from coke ovens thereto, of means for showering the gas in the main with water, whereby the water is heated by the gas, means for drawing off the gas from the main and washing and cooling the gas, means from drawing off from the main water heated by the gas therein and washing and heating the cooled gas therewith and means for returning the heated water to the main.

-In testimony whereof I have aflixed my signature, this 30th day of April, 1918.

BATES TORREY, JR, 

